This invention relates generally to porous inorganic particles useful as a packing material for column chromatography.
Because of the large surface area and high adsorption activity of porous inorganic particles such as silica gel, alumina and zeolite, they are widely used as a packing material to be packed in a gas or liquid chromatographic column. Since the adsorption activity of these inorganic particles considerably varies with their water content, however, a great care must be taken in handling them. In order to improve stability of the adsorption activity, various techniques have been developed for the modification of the porous inorganic particles.
For example, there is known silica gel whose surface is treated with octadecyltrichlorosilane (ODS) or octyltrichlorosilane for the modification with a C.sub.18 or C.sub.8 alkyl. The ODS-treated silica gel has improved stability to elution liquids such as methano-water and water-acetonitrile and is suitably used for reversed phase liquid chromatography. Silica gel whose surface is modified with an aminopropyl group, a cyanopropyl group or a diol group is also known and is commercially availble. There are, however, still numerous substances which cannot be separated in a satisfactory manner by these packing materials.